This invention relates to a new and improved sieve for sifting stones and gravel from garden soil by moving, vibrating, or shaking the new sieve across the top surface of a wheelbarrow or comparable vessel. The new sieve may also be used for sifting fine sand from coarse sand and gravel or for separating any fine product from a mixture. The invention is specifically designed to accommodate a wheelbarrow or other receiver whose shape is elliptical or oblong with rounded ends, although it may be adapted for use with a rectangular or square receiver.
Known garden sieves of this general type are shown in U.S. Pat. Nos. 4,350,584, Donington; 3,426,898, Cruickshank; 1,629,149, Citrin; 1,424,451, Crandall; 517,724, Beers; and 311,485, Gridley & Johnson.
The typical garden sieve consists of a flat rectangular frame, typically made of wood, with a wire screen or mesh affixed to the underside. Its principal use is to remove stones and gravel from garden soil in small quantities. It is utilized by propping it at an angle or setting it on a frame above the ground. The work is laborious and time consuming. Large processing equipment designed for singular, specific processing of far larger quantities than that contemplated herein exists but is uneconomical and unsuitable for ordinary garden use.
If a rectangular sieve is placed on an elliptical wheelbarrow pan a good portion of the surface area of the receiver is missed and/or the top plane of the receiver is open permitting contamination of screened material by unscreened material as it is shoveled into the sieve or screen. The modern wheelbarrow is typically not rectangular (or square) as 90 degree corners and vertical surfaces do not permit stacking of the pan or receiver for shipment. In addition, the typical wheelbarrow pan has compound curves to facilitate the mixing of concrete or mortar.